System and method for full duplex cancellation

• US 9,166,766 B2
• Filed: 09/22/2014
• Issued: 10/20/2015
• Est. Priority Date: 07/13/2012
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Jana, Rittwik, Aggarwal, Vaneet, Rice, Christopher W., Shankaranarayanan, Nemmara K., Duarte, Melissa, Sabharwal, Ashutosh
• Primary Examiner(s): Elliott, IV, Benjamin H
• Application Number:
  US14/492,588
• Publication Number:
  US 20150009868A1
• Time in Patent Office: 393 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04L 27/265 Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators H04L27/26524 takes precedence
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 5/143 for modulated signals H04L5/1469 takes precedence
• CPC Class Codes: H04L 5/1461 Suppression of signals in the return path, i.e. bidirectional control circuits

Abstract

Disclosed herein are systems, methods, and computer-readable storage media for enabling improved cancellation of self-interference in full-duplex communications, or the transmitting and receiving of communications in a single frequency band without requiring time, frequency, or code divisions. The system estimates the signal strength and phase of a self-interference signal, generates a cancellation signal based on this estimate, then uses the cancellation signal to suppress the self-interference before sampling received analog signal. After applying the cancellation signal, the system samples and digitizes the remaining analog signal. The digitized signal is then subjected to additional digital cancellation, allowing for extraction of the desired signal.

Claims

1. A method comprising:

determining a passive suppression of an interference signal, based on a previously estimated passive suppression stored in a database;

generating a negative estimate of the interference signal;

adding the negative estimate to the interference signal, to yield a residual interference signal; and

applying digital cancellation to the residual interference signal based on the passive suppression.

2. The method of claim 1, wherein the interference signal is received at a receiving antenna which is distinct from a transmitting antenna on a single device.

3. The method of claim 2, wherein the transmitting antenna comprises a plurality of transmitting antennas.

4. The method of claim 2, wherein the receiving antenna comprises a plurality of receiving antennas.

5. The method of claim 1, wherein the negative estimate added to the interference signal is an analog signal.

6. The method of claim 1, wherein the negative estimate is based on a subcarrier interference in the self-interference signal.

7. The method of claim 6, wherein the subcarrier interference indicates a variable self-interference between subcarriers.

8. A system comprising:

a processor; and

a computer-readable storage medium having instructions stored which, when executed by the processor, cause the processor to perform operations comprising;

determining a passive suppression of an interference signal, based on a previously estimated passive suppression stored in a database;

generating a negative estimate of the interference signal;

adding the negative estimate to the interference signal, to yield a residual interference signal; and

applying digital cancellation to the residual interference signal based on the passive suppression.

9. The system of claim 8, wherein the interference signal is received at a receiving antenna which is distinct from a transmitting antenna on a single device.

10. The system of claim 9, wherein the transmitting antenna comprises a plurality of transmitting antennas.

11. The system of claim 9, wherein the receiving antenna comprises a plurality of receiving antennas.

12. The system of claim 8, wherein the negative estimate added to the interference signal is an analog signal.

13. The system of claim 8, wherein the negative estimate is based on a subcarrier interference in the self-interference signal.

14. The system of claim 13, wherein the subcarrier interference indicates a variable self-interference between subcarriers.

15. A computer-readable storage device having instructions stored which, when executed by a computing device, cause the computing device to perform operations comprising:

determining a passive suppression of an interference signal, based on a previously estimated passive suppression stored in a database;

generating a negative estimate of the interference signal;

adding the negative estimate to the interference signal, to yield a residual interference signal; and

applying digital cancellation to the residual interference signal based on the passive suppression.

16. The computer-readable storage device of claim 15, wherein the interference signal is received at a receiving antenna which is distinct from a transmitting antenna on a single device.

17. The computer-readable storage device of claim 16, wherein the transmitting antenna comprises a plurality of transmitting antennas.

18. The computer-readable storage device of claim 16, wherein the receiving antenna comprises a plurality of receiving antennas.

19. The computer-readable storage device of claim 15, wherein the negative estimate added to the interference signal is an analog signal.

20. The computer-readable storage device of claim 15, wherein the negative estimate is based on a subcarrier interference in the self-interference signal.